There were many MMUs for 68ks at the time - 68000s and 68010s could use the '451, it was very slow and did use wait states, some people put TLB caches around th

There were many MMUs for 68ks at the time - 68000s and 68010s could use the '451, it was very slow and did use wait states, some people put TLB caches around them, Sun and many others built their own MMUs out of SRAM, there was guy who went around the Valley designing Sun-like MMUs for people they were all different, some were broken, the Lisa had a base and bounds MMU (like a PDP-11).. The 68000 couldn't restart page faults - people got around that a lot of ways, some put 2 68ks there and paused one while the other took the fault, mostly though most unixes of the day were swapping ones, the only traps that needed to be restarted were those that extended the stack down, and compilers could be persuaded to generate stack probe code. 68010s fixed that problem and were available around the time we started building paged systems. The 68020s could have an external PMMU (there was another done by Signetics, I think, it was a bit DOA), I think Sun still made their own. The 68030 pulled the PMMU on chip. At the time I worked for Unisoft, the company that did Unix for the Lisa, and A/UX for Apple, it was just one of about 150 Unix ports for other companies we did the bulk of them for 68Ks and most of those for those early 68000/010 - in short they were extremely popular, at the time every man and their dog were trying to make the next great workstation in their garages